ProjectSummary/Abstract Theproposedprojectisaninvestigationofthesynergisticactivityofantimicrobialcombinations against carbapenem-resistant Enterobacteriaceae (CRE). The principal investigator, Dr. Thea Brennan-Krohn, recently completed fellowships in Pediatric Infectious Diseases and in Medical Microbiology and is now an Instructor at Harvard Medical School and a post-doctoral fellow at BethIsraelDeaconessMedicalCenter.Sheisinterestedinimprovingmethodsfordetectionand characterizationofantimicrobialsynergyinordertoguidethetreatmentofpatientsinfectedwith highly resistant pathogens. Her career goal is to become a leading investigator in the development, implementation and interpretation of tests for detection of antimicrobial synergy. During the award period, she will obtain a Master of Science in Pharmacology and will pursue courseworkinclinicalandtranslationalresearch.Theproposedresearchwillbecarriedoutunder the mentorship of James Kirby, MD, D(ABMM), an NIH-funded investigator at Beth Israel DeaconessMedicalCenterwhoselaboratoryinvestigatestopicshighlyrelevanttotheproposed project, including the development of novel antimicrobial susceptibility testing methods and the investigationofnewtherapeuticsforCRE.Dr.Brennan-Krohnwillbesupportedduringtheaward periodbyanadvisorycommitteethatincludesDr.GeorgeEliopoulos,aworld-renownedexpert onantimicrobialsynergy.Intheproposedproject,Dr.Brennan-Krohnwillinitiallytestantimicrobial combinations against a comprehensive collection of clinical CRE isolates in order to establish combinatorial spectra of activity. For this part of the project, she will use an automated checkerboard array microdilution method that makes use of the HP D300 inkjet printer-based dispensingsystem.Shewillnextdevelopanovel,fluorescenttime-killsynergyassayinorderto investigatethebactericidalkineticsofsynergisticcombinations.Finally,shewillinvestigatethein vivo efficacy and PK/PD parameters of the most effective combinations using an immunocompromisedmousemodelofCREinfection.Ultimately,theenhancedunderstandingof synergy as well as the technology developed and validated during the proposed study are expectedtoinformthedesignofprospectiveclinicaltrialsofcombinationantibiotictherapyand toestablishsimple,rapidsynergytestingplatformsthatwillforthefirsttimeprovidesynergydata thatcanbeusedinaclinicallyactionabletimeframetoguidepatientcare.